Atopic dermatitis is an abnormal syndrome of the skin which generally exhibits unknown severe pruritus and is also complexly accompanied with xeroderma, erythema and inflammation on the skin (Lancet. 1998; 351:1715-1721). Atopic dermatitis is a chronic disease causing great inconvenience to the patients' long-term lives, and commonly affects infants or young children. This disease affects 10 to 15% of infants and young children. Looking at the occurrence of atopic dermatitis in a group of atopic dermatitis patients, 60% of the atopic dermatitis occurs in infants aged one or less, and 85% of the atopic dermatitis occurs in young children aged five or less (Lancet. 1998; 351:1715-1721). 40% of child patients suffering from atopic dermatitis improve with age, but the incidence of atopic dermatitis in adults has also increased to approximately 1 to 3% of all adults due to air pollution, environmental pollution and the like caused by sudden industrialization (Immunol. Allergy. Cli. North Am. 2002; 22:1-24), which is two or three times that prior to industrialization (Lancet. 2003; 361:151-160). For this reason, many researchers have been interested in alleviating the clinical symptoms of atopic dermatitis.
The clinical symptoms of atopic dermatitis differ according to individuals. However, atopic dermatitis patients have some representative symptoms: the first being severe itching, the second displeasure due to the patient's skin remaining dry, and the third loss of defense functions in the skin surface due to the dry skin, which facilitates easy penetration of stimulants from the outside and causes an inflammatory response due to rejection of the stimulants by the skin (Lancet. 1998; 351:1715-1721; J. Pediatr. Health Care. 2002; 16; 143-145).
Many studies on the causes and treatment of atopic dermatitis have been conducted so far. However, exact causes and effective treatment of atopic dermatitis have not been clearly established due to the complexity of atopic dermatitis and conflicting data.
Steroids, local anti-inflammatory preparations such as tacrolimus and pimecrolimus, anti-histamine agents, and immunosuppressants such as cyclosporine have are therapeutic agents developed so far that are used to treat atopic dermatitis. Also, photochemotherapy using a hypoallergenic humectant and ultraviolet A has been used clinically as adjuvant therapy. However, such therapy or therapeutic agents are not a basic cure but merely aid in regulating a proper level of symptoms, and have not yet completely satisfied the demands of atopic dermatitis patients.
To meet such demands, the present inventors developed a therapeutic agent for treating atopic dermatitis including glucosamine as an active ingredient, wherein the glucosamine is a natural substance that is a commercially available transglutaminase inhibitor whose safety has been already approved (Korean Patent Publication No. 2008-0035997). However, glucosamine has a therapeutic effect only on some individual patients, and its therapeutic effect is poor on severe atopic dermatitis patients. Meanwhile, immunosuppressants such as cyclosporine have been used for severe atopic dermatitis patients that are resistant to conventional therapeutic methods. Such immunosuppressants exhibit excellent effects, but have problems regarding side effects such as nephrotoxicity, gingival hyperplasia, hypertrichosis, neurotoxicity, hypertension, hyperlipidemia, glycosemia, hyperkalaemia, hyperuricemia, hemolytic uremic syndromes, and infections. Further, although it is difficult to administer an immunosuppressant for a long period of time due to its side effects, the atopic dermatitis returns to its original severe state when administration of the immunosuppressant is discontinued.